Rotary pump



H. L. NASH ROTARY PUMP Dec. 22, 1942.

Filed June 6, 1940 3 Sheets-Sheet 1 INVENTOR.

HUM PHREY L. NASH.

' o mxmww ATTORN.

' Dec. 22, 1942. H. L NASH 2,306,276

ROTARY PUMP Filed June 6, 1940 3 Sheets-Sheet 2 I u :IE

32 i L: 5-. 11 4 FIE-.12

INVENTOR.

HUMPHREY LNASH.

ATTpggwEYs H. L. NASH ROTARY PUMP Dec. 22, 1942.

1940 3 Sheets-Sheet 5 Filed June 6,

HIE-.16

II'E.15

' INVENTOR.

V HUMPHREY L.NASH.

- ATTORNEY Patented Dec. 22, 1942 UNITED "STATES PATENT OFFICE j Vasoazve g r ROTARY PUMP Humphrey L. Nash, Shaker- Heights, OhioApplication June 6; 1940, s m No. 339,154

' 11 Claims. "(01. 103-137) This invention relates as indicated torotary pumps, and more particularly to vane type rotary pumps operativeto provide non-pulsating delivery without at the same time .oc'casioningmechanical shockto the vanes.

In modern 'carbureters for internal combustion engines, and especiallyairplane engines, it is becoming of more and more importance to providea steady even flow of fuel under constant pres- As pointed out. inCurtis Patent sure thereto. No. 2,165,963, prior art workers had notfound it possible to construct a vane type rotary pump which would bothprovide non-pulsating delivery and yet be free from mechanical shock.Curtis thendiscloses one solution of this problem in which special camguides are employed to conf duct the vane tips-from the -arcuatelycurved pumping zone to the arcuately curved sealing zone, and viceversa. However, this type of pump chamber is somewhat complex ofconstruction and'does not permit the employment of less than six vanes,which fact, as when pumping a volatile liquid such as gasoline, may tendto cause vapor lock due to entrapment and violent working of a portionof such liquid.

. It is therefore a primary object of this invention to provide a vanetype rotary pump havinga non-pulsating delivery and yet free frommechanical shock in operation. V v V Another object of this invention isto provide a pump of the type above indicated which will be simple andinexpensive to manufacture efllcient in operation. 7

Another object is to provide a non-pulsating rotary pump in which asingle vane may be suilicient in a chamber. I

' Other objects of this invention will appear as the descriptionproceeds.

vTo the accomplishment of the foregoing and related ends, saidinvention, then, consists of the means hereinafter fully described andparticularly pointed out in the claims. Y

The annexed drawings and the following description set forth in detailcertain mechanism embodying the invention, such disclosed meansconstituting, however, but one of various me'- chanical forms in ventionmay be used.

In said annexed drawings: 7

Fig. 1 is a cross sectional view axially of the rotor of one form ofpump embodying my invention;

which the principle of the in- 2-2011 Fig. 1;

Fig. 3 is a sectional view ofthe intake valve 1 of such pump taken alongthe line 3-3 on Fig. 1;

Fig. 4 is a sectional view taken through one chamber of such pumpaldngthe line 4-4 on Fig. 1; v

Fig. 5 is a sectional view taken through the outlet valve of such pumpalong the line 5-5 on Fig. 1;

Fig.6 is a sectional view of the other chamber of such pump taken alongthe line 8-6 on F18. 1;

Fig. 7 is a sectional view taken axially of the rotor oi another pumpembodying my invention,

Fig. 10 is a sectional view through one pump j chamber taken alongtheline lfl-lli on Fig. 7; Fig. 11 is a sectional view taken through theother pump chamber along th line l l-il on and r m. a is a sectionalview through the casing Fig. 12 is a sectional view of the inlet valvingmeans for such last named chamber taken along the line' l2-l2 on Fig. 7;1

which ports are provided through the vanes;

Fig. 14 is a transverse sectional view through such pump taken along'the line ll-ll on Fig.

Fig. 15 is asectional view taken li-li on Fig. 13; and 1 Fig. 16 is asectional view along the line i 6- on Fig..13 showing the dischargeoutlet.

Referring now more particularly to said drawlugs, and especially Figs. 1to 6, the embodiment 'of my new invention there illustrated comprises apump'casing I in'which is journalled a rotor 2 adapted to be driventhrough drive shaft 3. "as shown in Figs. 1 and 2, a central wall 4divides the interior of such casing into two pump cham bers 5 and 6. Ineach of such chambers respectively and reciprocable in the rotor areunitary vanes 'l' and l, the bore of each of said chambers, i. e., thecam track followed by the vane tips, describing equal limacon curves.

7 Also formed in said casing parallel to the axis of the rotor are twocanals 9 and ill, the first communicating with inlet passage II and thelatterwithoutletmfl. Canallallooom- Fig. 1a is a sectional view axiallyor the as r of another pump embodying my invention in along linemunicates directly with chamber 6 and indirectly through passage l3 andport l4 ori5 in rotor 2 with chamber 5. Likewise, chamber 5 communicatesdirectly with canal in (see Fig. 4) and chamber 6 indirectly thereto byway of port l5 or I! in the rotor and passage i8. On the inlet side ofchamber 6 and on the outlet side of chamber 5 cam guides 19 and 20 areprovided respectively for the vane tips. 7 r

The operation of the above'described embodiment of my new pump may nowbe explained.

As rotor- 2 turns in aclockwise' direction, as a view in Figs. 2 to 6,inclusive, liquid willbe drawn in to chamber 5 through passage i I,canal 9,

inlet passage l3 and either port I4 or i5 depend-.

ing on which vane tip is passing through the pumping zone. a As shownin'Fi'gs. 4'and 6,the

, rotate in a clockwise direction, liquid is forced over into theright-hand part of chamber 5 as the lower end of vane 8 risesupwardly inthe leftlower ends of the vanetips are respectively just entering andleaving the pumping zone. As the vane tip moves through the pumpingzone, the port in the rotor rearwardly thereof will be in communicationwith passage 13 and liquid will be drawn in behind such tip.Slmultaneously, this vane tip will be discharging liquid from the pumpchamber by way of canal in to'passage ',I2.

Referring now to Figs. 5 and 6, as the tips of vane 2 are reciprocatedin chamber 5 by revolution of the rotor, liquid is'drawn directly intosaid chamber from canal .8 and discharged through port" or II, dependingon which end 7 Thus'it will be seen that the path of the fluid beingpumpedis asfollows: I

It enters the casing i through inlet pipe ii and flows into the passagel3, which is formed in the casing andis shown in Figures 3 and l. Theparts being'in the positions shown, permit the fluid to pass throughport i4 in rotor 2 and flow from port 14 outinto chamber 5 as this portmoves from the lower part of such chamber to the. upper art of suchchamber. The flow is occasioned by chamber 5 being evacuated, thuscausing the liquid .being pumped to flow upwardly out of port, l4 intochamber .5 when.

the parts are in the position shown in Figure 4. Vane I, as the rotorcontinues in a clockwise directiomnow begins its pumping stroke and itforces the liquid out of chamber 5 and up through canallO, because porti4 has been closed bythe ,30 of the vane is pumping, to passage i8 andthence to canal l0 and discharge passage l2.

.casing it being understood that the parts are slightly rotated in aclockwise direction from the position shown in Figure 4. As the vane Icontinues in aclockwise direction, the port I5: is placed incommunication with the casing inlet passage l3, but the liquidbeingpumped cannot be forced into the port 15 since the port has passedthe casing shouldershown in the lower part of Figure 4. Obviously then,the liquid is forced out into the passage which lies radially outward ofthe cam track 20. It is to be noted that at this time, the port i4 doesnot communicate with the inlet passage l3 and that the opposite end ofthe vane is forcing liquid out of chamber 5 andthat the only outlet isthe canal il. It is, also to be remembered that the vane I, as viewed inFigure 4, will begin to exert pumping action as the rotor revolves in aclockwise direction and that for all practical purposes, the 7 From theforegoing it will be understood exdescribes an equal limacon ,curve.

hand part of chamber 6,'as shown in Figure 6. However, since the port i5it is communication with outlet passage IS, the liquid passes from theright-handportionof chamber'i axially along port l6 and then throughoutlet passage [8 to outlet canal l0. I

, It is to be noted that perfect balance is obtained since there is acounterpart for every part and in each'case, the action is opposite ineffect and in volume.

It will 'thus'be seen that the rate of change of fluid discharge fromone. chamber is always 'equal to butopposite in sign to'that. from theothervchamber so that thecombined discharge of passage I2 is always aconstant. Since the bores, or cam tracks of such chambers describe equallimacon curvesrthere will of.course be no 'mechanical shock and unitaryvanes may be employed, as well known'in the art. By the employnient ofoppositely. disposed pumping zones, which thus complement each other,and the provision of inlets and outlets respectively in communication,it is therefore possible to obtain. the

whichcominunicates directly with outlet passage 29. As in thepreviouly'described embodiment of the invention, the bore of each pumpchamber However, there are neither direct inlets nor outletsto or fromsuch chambers. Instead, outlet ports and 3| are provided initherotor asshown in Figs. 8, 10and 11, such ports being in communication withpassage 28 except for aportion of thesuch ports affording constantcommunication between passage 28 and chambers 24 and 25, even whenprimary outelt ports 3i and .30 are .re-

spectively sealed. Chamber. 24 is .in communication withinlet passage 34and inlet conduit 35 by way of port 36 in the rotor. A small auxiliaryport 31 is'also provided which maintains constant communication betweensaid chamber and said passage even when primary port 36 is sealed. Asimilar intake port 38 and an auxiliary port connects chamber 25 withintake passage 40 and intake conduit 4|. Reciprocably mounted in therotor is an offset unitary vane 42 one end of which travels in contactwith the peripheral I through the sealing zone, as illustrated in Fig.11

and during a portion of the revolution immedi ately preceding thispoint, intake port 38 is closed, as shown in Fig. 12, and for aconsiderable portion of the revolution of the rotor the entire intake isthrough auxiliary port 39 which, however, quite suflices since the vaneend during this portion of the revolution of the rotor is discharging arelatively small amount of fluid. Similarly the discharge from chamber25 through port 3| to outlet valve 28 is cut off for a consid erableperiod, as shown in Fig. 8, all fluid passing through auxiliary port 32.It is apparent, therefore, that there will be a very brief moment,defined by the thickness of the wall separating the primary andauxiliary ports, during which the auxiliary inlet port will 'be open tothe inlet valve and the auxiliary outlet port simultaneously incommunication with the outlet valve. However, due to the small size ofsuch auxiliary ports and the extremely brief period during which theyare in communication, any pulsation which might occur is so small as tobe imperceptible;

It will of course be understood that inlet conduits 35 and 4| may be indirect communication with each other as by joining them to the same leadfrom a fuel tank or the like. 1

As described and explained above, a novel pump has thus been providedwhich is capable of constant non-pulsating, delivery without mechanicalshock to the mechanism, and, further, in which any possible loss ofpower due to the drag of a vane endthrough the discharge zone isavoided. It is also obvious that a plurality of more than two chambersmight be employed without departing from the scope of this invention,and likewise, that my new pump may instead be employed as a motor. Whilethe outlets from. the pumping chambers must be in com-' munication inorder to provide non-pulsating delivery, it is not necessary that theinlets com municate, although such' will generally be the case. r

The embodiment of my invention illustrated in Figs. 13 to 16, inclusive,afi'ords a number of additional advantages including simple valvingmeans and an avoidance of ports in the rotor at points spaced from thevanes. As best shownin Fig. 13, this embodiment comprises a pump cas-'ing 43 in which is journalled a divided rotor 44a and44b adapted to bedriven through dive shaft 45. The interior of such casing comprises pumpThe intermediate portion 58 of said offset vane passes through openings59a and 59b in the inner faces of said rotor segments, the vane'servingto position such segments axially within the casing and also affordingthe means whereby segment 44b is maintained in driven engagement withsegment 44a.

An inlet passage 611 communicates with a canal 6| in the casing which inturn connects with chambers 62 and 63 disposed axially of said rotorsegments. In the outer ends of each of said rotor segments are inletports such as 64 in constant communication with chambers 52 and 63respectively. The vane ends are partially cut away, as shown in Fig. 15,so that as the rotor revolves in a clockwise direction as viewed in Fig.15 liquid may enter behind the vane through port 64 and pass intochamber 46. Liquid on the pressure side of the vane will be forced outof such chamber by way of the outlet port 65 in such vane and thencethrough opening 59a into cavity 50 from which it flows through holes 52to chamber 53 and outlet passage 54. Of course as a vane end is forcedinto the rotor as the'latter rotates, the rocker tip will graduallyclose both the inlet and the outlet ports in such vane end, until suchports are simultaneously completely closed. It will thus be seen that apump has been provided in which but a single vane end is employed in achamber, such vane end pumping continuously with rotation of the rotorexcept for the moment when it is entirely retracted in the rotor. Sinceeachvane endis pumping in a complementary chambers 46 and 41' separatedby partition walls 48 and 49 which form a discharge collecting cavity 50therebetween circumferentially bounded by a spacer band 5| pierced byholes 52 afiording communication between cavity 50 and outer mounted inthe respective segments of said.

divided rotor is a unitary offset vane 55 having rocker tips 56 and 51contacting the limacon curve liners of said pump chambers 46 and 41.

pumping zone,} the joint discharge of the two chambers will be uniformand pulsationless. Since limacon curve chambers are employed there willalso be no mechanical shock. The segments of the rotor may be joined toform a unitary assembly, if desired.-

In addition to the obvious advantages of the 4 above describedconstruction, it is apparent that such construction makes many otherimprovements possible. For instance, the intermediate portion of thevane may be formed as; a separate element fitting in sockets inthe two.true vanes. The small amount of play therebetween would permitv theautomatic, take-up of. wear on the rockers. 7

When employing a pluraity of limacon .pumping chambers in accordancewith my invention it is apparent that various combinations are possiblesuchv as one large chamber and two small chambers, the vanes in the twosmall chambers pumping in zones complementary to the vane or vanes inthe large chamber, the relative sizes of such chambers being so chosenas to provide are not quite oppositely disposed in relation to therespective limacon curve liners there will be a degree of pulsationalthough, of course, not as serious as in a pump not having evenpartially complementary pumping zones. Unless the vane ends'a'redirectly opposed, unitary vanes cannot be employed and spring backedvanes orthe like must be used.

In the past, the method most generally employed to reduce pulsation wasto provide a large number of vanes with resultant increase in as semblydimculties and wear in use. As above explained, a pump maybe constructedin accordance with my invention employing only one vane, such pump beingwell-balanced, long-wear-= ing and eflicient in operation. One end ofsuch vane pumps in one chamber, the other end in the other chamber. Itis, of course, possible to employ a' plurality ofsuch unitary vanes ifdesired. 7

While it is believed that those skilled in the art will have littledlfllculty in understanding the above explanation of my invention, abrief summary of the mathematics involved may be helpful. The formulafor a limacon curve is (such point also being the 'centerofrotation of ithe rotor). Such curve is well known and has long been employed inrotary pumps i ce it is 3. In a vane type rotary pump, at least twolimacon pump chambers, a rotor in eachof said chambers, a vane'in eachof said rotors and reciprocable' therein, the ends of said vanes incertain" oi said chambers being disposedl80 apart relative in thecorresponding ends of the vanes 'in the other" said chambers in relation'tothe limaconcurves engaged thereby so that therotation of said rotors.

the only curve permitting the use ofunitary vanes passing through thecenter of the rotor. However, due to the shape of such curve, thevolume'of liquid being discharged by any vane end during'a stateddegreeofangular-rotation will vary'radically with consequent'pulsationin the discharge line. While this situation maybe somewhat amelioratedby the provision of a larger number of vanes, other complications thenarise without having, obtained truly pulsation less delivery. Prior artworkers, such as Curtis, therefore'turned to other curves-andcombinathus of curves to attackfthe problem; But by employingmyinvention absolutely pulsationless delivery may be obtained withoutabandoning the otherknown advantages of limacon curve Dumps.

Othermodes ofapplying the principle of :my

invention may be employed instead of the one explained, change beingmade as regards the mechanism herein disclosed, provided the meansstated by *any of the following claims or the equivaent of such statedmeans be employed I therefore particularly point out and distinctlyclaim as my invention'i v1. Ina vane type rotary pump, at leasttwolimacon pump chambers, a rotor in each of said chambers, a vane in eachof said rotors and reciprocable therein, the corresponding ends of saidvanes being disposed 180? a art relative to the respective limaconcurves engaged thereby so that the sum of the eflective pumping areas ofsaid vanes is at all times a constant, fluid inlet means communicatingwith said chambersrearwardly of such vane ends, fluid outlet meanscommunicatingwith each of said chambers forwardly of such' vane ends,said outlet means being in communication with each other, and

means operative to synchronize the rotation of saidrotors. I

2. In a vane type rotary pump, a plurality of limacon pump chambers,rotorstherein, a vane in each of said rotors and reciprocable therein,the ends of said vanes in certain of said chambers being disposed "180apart relative to the corresponding ends of the'vanes in the other saidchambers inrelation to the respective limacon curves'engaged thereby andthe size and number of said chambers being so chosen that the sum of theeflective pumping areas of said vanes is at all times a constant, fluidinlet means communicating with. said chambers rearw'ardly of such vaneends, fluid outlet means communicating with each of' saidchambersforwardly of 1 such vane ends, said outlet means being incommunication with each other, and means operative to synchronize therotation of said rotors.

, 4. In a .van'e type'rotarypump, at least two limacon-pump chambers, arotor in eachot said chambers, a vane'in each of said rotors andreciprocable thereimnot more than one vane end in each chamberbeingoperative as a pumping element. atany onetime, the ends of saidvanes in, certain of said chambers being disposed apart relative to'thecorresponding ends of the vanes-in the other said chambers in relationto the 'limacon curves engaged thereby, fluid inlet means passingthrough said rotors-and entering said chambers rearwardly of such vaneends, fluid outlet means passing through said rotors and communicatingwith said chambers forwardly of such vane'e'nds, and means operative tosynchronize the rotation of said rotors.

5; In a vane type rotary pump, a plurality of limacon pump chambers ofequal'bore, a rotor in' said chambers, vanes in said'chambers andreciprocable in said rotorthe ends of said vanes operative as pumpingelements at any one time in certainv ofv said chambers being oppositelydisposed to such endsin the other saidchambers in relation to thelimacon curves of said respective chambers, inlets to said chambers, andoutlets from said chambers in communication with each other. I

,6. In combination, two limacon pumps respectively comprising casings ofequal limacon bore in axial alignment, rotors in said casings, aunitary.vane slidably mounted in said rotors, one end of said vane engaging theinner surface of onefof said casings andthe other end or said vaneengaging the inner surface ofthe other or said casings at a pointdiametrically opposite on the limacon'curve thereof, inlet ports throughsaid rotors communicating with the interior of said casings rearwardlyof said vane ends, and outletports through said rotorscommunicating withthe interior 0! said casings forwardly of said vaneends, said outletports being in communication with-each other. 7 I

, 7; In a vane type rotary pump, adjacent paired limacon pump chambersmaxial alignment, a rotor revoluole therein, a unitary onset vanereciprocabie in said rotor with one end'oi saidvane inshding engagementwith, the suriaceot one of said chambersand'the other end in slidingen'- gagement with the surface of the other'ot said chambers at adiametrically opposite point thereon, inlet ports through said rotor andcut-away portions of the suction sides of said vaneends,

outlet ports through cut-away portions of the pressure sides of saidvane ends and through rotor, and rocker tips for vane ends operative toseal said respective inlet and outletports charge from said outlet portsbeing conducted to a common passage. 1

8. In 'a vane type rotary pump, two simila pump chambers, rotorseccentrically disposed in said chambers, the inner peripheries of saidchambers comprising curves in which the sum of the lengths of theopposite polar coordinates is a constant, the poles of such curves beingthe centers of rotation of said rotors, a vane in each of said rotors insliding engagement with the inner peripheries of said respectivechambers, only a single vane end being operative as a pumping element ineach of said chambers at any one time, such operative vane ends beingoppositely disposed relative to the curves of the inner peripheries ofsaid respective chambers, inlets to said chambers, outlets from saidchambers in communication, and means operative to synchronize therotation of said rotors.

9. In a vane type rotary pump, two similar pump chambers, a rotoreccentrically disposed in said chambers, the inner peripheries of saidchambers comprising curves in which the sum of the lengths of theopposite polar coordinates is a constant, the poles of such curves beingthe center'of rotation of said rotor, an ofiset unitary vane in saidrotor, one end of said vane being in sliding engagement with the surfaceof one of said chambers and the other end in sliding engagement with thesurface of the other of said chambers at a diametrically opposite pointon the curve thereof so that the sum of the extension of the vane endsfrom the rotor is at all times a constant, inlet ports through saidrotor on the suction sides of said vane ends, and outlet ports throughsaid rotor on the pressure sides of said vane ends, said outlet portsbeing in communication.

10. In a sliding vane type rotary pump, two

similar pump chambers, rotors eccentricallyayt 5 posed in said chambers,the inner peripheries of said chamberscomprising curves in which the sumof the lengths of the opposite polar coordinates is a constant, thepoles of such curves being the centers of rotation of said rotors, avane reciprocable in each of said rotors in sliding envane ends, saidoutlet means being in communication with each other, and means operativeto synchronize the rotation of said rotors.

11. In a sliding vane type rotary pump, two similar pump chambers,rotors eccentrically disposed in said chambers, the inner peripheries ofsaid chambers comprising curves in which the sum of the lengths of theopposite polar coordinates is a constant, the poles of such curves beingthe centers of rotation of said rotors, a vane reciprocable in each ofsaid rotors in sliding engagement with the inner peripheries of saidrespective chambers, the corresponding ends of said. vanes beingdisposed 180 apart relative to the respective curves engaged thereby sothat the sum of the extension of the operative vane eiids from therotors is at all times. a constant, fluid inlet means communicating withsaid chambers rearwardly of, such vane ends, fluid outlet meanscommunicating with each of said chambers forwardly of such vane ends,said outlet means being in communication with each other, and meansoperative to synchronize the rotation of said rotors.

HUMPHREY L. NASH.

